5-29
5-6 Full Closing Control
OMNUC G5-SERIES AC SERVOMOTOR AND SERVO DRIVE USER'S MANUAL
5
BASIC CONTROL Mode
External Feedback Pulse Dividing Ratio Setting (Pn324, Pn325)
Set the dividing ratio for the encoder resolution and external scale resolution.
Check the number of encoder feedback pulses and the number of external scale output pulses
per motor rotation, and set External Feedback Pulse Dividing Numerator (Pn324) and External
Feedback Pulse Dividing Denominator (Pn325) so that the following formula works out.
If this divider setting is wrong, there will be deviations between the position calculated from
encoder pulses and the position calculated from external scale. If the movement distance is
long, these deviations accumulate and cause an internal/external feedback pulse error counter
overflow level error.
Setting Examples
Ball screw pitch 10 mm
External scale resolution 0.1
μ
m
Encoder resolution 20 bits
Parameter
number
Parameter name
Explanation
Setting
range
Unit
Pn324
External Feedback
Pulse Dividing
Numerator
Set the numerator of the external scale
divider setting. Normally, set the number
of encoder output pulses per motor
rotation. If the set value is 0, the encoder
resolution is set automatically.
0 to 2
20
-
Pn325
External Feedback
Pulse Dividing
Denominator
Set the denominator of the external scale
divider setting. Normally, set the number
of external scale output pulses per motor
rotation.
1 to 2
20
-
Pn324 Number of encoder output pulses per motor rotation
=
Pn325 Number of external scale output pulses per motor rotation
Servomotor
encoder resolution: 20 bits/rotation
10 mm
Ball screw
Ball screw pitch 10 mm
1 Rotation
External scale
resolution: 0.1
μ
m
External Scale Output Pulse Per Motor Rotation (Pn325)
10 [mm] / 0.1 [
μ
m/pulse]
=
100,000 [pulse]
Encoder Output Pulses per Motor Rotation (Pn324)
20 bits
=
1,048,576
Pn324 Number of encoder output pulses per motor rotation 1,048,576
=
=
Pn325 Number of external scale output pulses per motor rotation 100,000